1. Field of the Invention
The present invention relates to a sheet handling apparatus, an image forming system, and a sheet reception control method.
2. Description of the Related Art
There is a conventionally-known apparatus called a finisher that includes a stapler that stacks the sheet discharged from an image forming apparatus on a staple tray, aligns the sheet in a conveying direction (i.e., a vertical direction) of the sheet and in a direction (i.e., a width direction) perpendicular to the conveying direction, and then binds the sheets. When the stapler performs end-face binding, the sheet is in contact with and is held by a reference fence, which defines the position of the sheet in the sheet conveying direction, during end-face binding. At that time, the stapler moves along the edge of the sheet (usually, the trailing edge of the sheet) in a direction perpendicular to the sheet conveying direction so that the binding position can be changed.
Such a technology for positioning by using the above reference fence is disclosed in Japanese Patent Application Laid-open No. 2008-156073 and Japanese Patent Application Laid-open No. 2009-263127, for example.
In order to eliminate the need for the structure for retracting a binding device and the driving source for a trailing-edge fence so as to achieve a reduction in cost and space, for example, Japanese Patent Application Laid-open No. 2008-156073 discloses a sheet handling apparatus that performs a predetermined process on a conveyed sheet material and then discharges the sheet material. The sheet handling apparatus includes an intermediate tray that temporarily receives a conveyed sheet material to be stacked thereon; a trailing-edge fence that is in contact with the trailing edges of the sheet materials stacked on the intermediate tray and conveys the sheet materials to the transfer position; a release claw that takes over the conveyance from the trailing-edge fence downstream of the transfer position and then conveys the sheet materials from the intermediate tray; and a conveyance driving mechanism that drives the trailing-edge fence and the release claw by using the driving force from one motor.
Furthermore, Japanese Patent Application Laid-open No. 2009-263127 discloses a sheet post-handling apparatus that ensures that the leading edge of the sheet is in contact with an end stopper for alignment. The sheet post-handling apparatus includes a discharge roller that conveys the sheet discharged from the image forming apparatus so as to discharge and stack the sheet on an alignment tray that is arranged at a tilt; and includes a movable end stopper that brings the trailing edge of the sheet, which has been discharged into the alignment tray, into contact with the contact surface of the reference fence while the leading edge of the sheet is pressed so that the sheet is aligned in the conveying direction. The degree of pressure of the end stopper in the sheet conveying direction is variable.
As described above, when the sheets are sequentially stacked on the staple tray, which performs a staple process, and then subjected to a binding process, the trailing edges of the sheets come into contact with the reference fence that serves as a reference so that the trailing edges of the sheets are aligned. Such an operation is widely performed. In this type of sheet handling apparatus, the sheet discharged into the end-face binding processing tray Falls due to gravity and comes into contact with the reference fence. At that time, according to the condition of sheet, such as a soft sheet or heavy sheet, there is a possibility that, when the sheet is brought into contact with the reference fence, damage to the edge face of the sheet due to the impact to the reference fence. It is considered that the impact damage is caused by the kinetic energy of the sheet that is generated when the sheet comes into contact with the reference fence. Particularly, noticeable impact damage occurs if the falling velocity of the sheet is large, if the sheet is heavy, or if the sheet becomes easily damaged.
Therefore, there is a need for a sheet handling apparatus capable of minimizing the impact on the edge face of the sheet when the sheet comes into contact with the reference fence to prevent the occurrence of impact damage.